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  1. #1
    silvercrxsir's Avatar
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    cant fig out this lean condition need help

    01 gp800r,Ran it for 1min wide open on new plugs shut it down plugs are both white,ski runs pretty good,all stock except for riva flame arrestors,still have choke plates stock main jets were 150s,I'm running 157.5 and high needles are open pretty much all the way,running amsoil dominator 40:1 carbs were rebuilt with mikuni kits I did notice if it sits the the gas cap will hiss upon removal,but after running it there's no pressure in the tank.I tried press testing tank but it doesn't leak,is there anything in the carbs that could be causing this,check valve for tank is new and works properly so are fuel lines


  2. #2
    silvercrxsir's Avatar
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    Fuel filter is also new oem

  3. #3
    silvercrxsir's Avatar
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    Compression is at 120 for both and I vacuum tested the motor with no.air leaks,its actually sealed very well

  4. #4
    Yamaha artisan Cutlass's Avatar
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    Do the plugs have any color on them or are they just mostly white? Do you have any pics you can post?
    Maybe thats not quite enough run time to put some color on them.

  5. #5
    silvercrxsir's Avatar
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    I would say they have 30min total on them,what inside the carbs could be causing me to have no tank pressure when running,after running it theres no pressure,then I get it home after it sits an hour there is pressure its got over 3/4 tank so it should pressure up

  6. #6
    Yamaha artisan Cutlass's Avatar
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    Man, I don't know. Those plugs just look new, like maybe they don't have enough run time on them. Lean plugs look more off white...those plugs just look new bright white. Reading plugs can be tricky and inconclusive sometimes. I just prefer not to read plugs. Reading piston wash works better, but thats just an overall picture or rich/lean from idle to WOT. And it take many hours to show up nicely.
    As for tank pressure, my ski never has any tank pressure or vacuum and it runs/starts perfectly fine. I don't buy into the whole tank pressure thing. But obvious tank vacuum (ie tank isn't venting) is a definitely a problem that can happen.

  7. #7
    silvercrxsir's Avatar
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    After reading just about every single carbs sticky and post I pulled the carbs back out disassembled and inspected them and found a few areas of concern.since any guides for carbs rebuilding are kinda tough to find when I first overhauled them I used the one off the Sbt site,bad idea.that guide sucks.I found a link on here and it mentioned checking the ARM height with a razorblade and it needed to be level and mine was sticking up,so there's one issue.another was after reading oside bills excellent sticky on check valve install it says in a small pic how they are pressed on a curved sheet and the side with the marker faces away from the pump body,every guide I read even the mikuni manual or the sheet that comes in the kit doesn't say anything about this,I just thought they put the mark there to make it more visible or something so those could have been installed wrong,third issue was when I checked pop off I never let it sit with pressure to check for leaks,I just tested 3 times then called it good,come to find out the pump side wouldn't completely seal,so I went back cleaned the surfaces up better and fixed any leaks on my homemade tester and now they hold so hopefully now that fixes it

  8. #8
    Let me guess...leaking at the base of the fuel pump . You did say those were genuine Mikuni rebuild kits right?

  9. #9
    silvercrxsir's Avatar
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    Yup genuine mikuni kits

  10. #10

    Re: cant fig out this lean condition need help

    did u replace the needles and seats when you rebuild the carbs?

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